<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <p>1231231</p>
    <p>1231231</p>
    <p>1231231</p>
    <span>lalal</span>
    <button onclick="fn1()">click</button>
    <form action="">
        <input onkeyup="fn2()" name="aaa" type="text">
    </form>
    <script>
        function fn1 () {
            var e = e || window.event;
            console.log(e);
        }

        function fn2() {
            console.log(event);
        }
    </script>
</body>
</html>